Fuel burner



Jan. 12, 1954 F. H. coRNELlus FUEL. BURNER 2 Sheets-Sheet l Filed May27, 1949 .FRANK H. CORNELIUS AGENT Filed May 27, 1949 2 Sheets-Sheet 2mi LS1 i 2 A f1 "53 G A ml` I v \I o /l i) o INVENTOR.

FRANK H. CORNELIUS layoff/ffl@ AGENT Patented Jan. 12, A1954 UNITEDSTATES PATENT OFFICE FUEL BURNER Frank H. Cornelius, Shade Gap, Pa.

Application May 27, 1949,` Serial N o., 95,789

5 Claims.

The present invention relates to an improvedV method of and apparatusfor burning fuel, particularly liquid fuel, such as oil, under pressure.

Oil burners which burn oil under pressure and which are of the typecommonly called gun type or gun burners derive their name from therelatively long air blastv tube which has the appearance of a gunbarrel. Such a burner includes a pump connected to an atomizing nozzlecentrally disposed at the inlet end of the tube for discharging a streamof atomized oil. A fan supplies la relatively large volume of air to theinlet end of the tube. An igniter is usually mounted near the nozzle forigniting the fuel oil and the velocity of the air stream blows the fueloil through the tube. Some burning takes place in the tube, but most ofthe burning takes place after the stream of air and fuel oil pass fromthe tube into a combustion chamber. These gun type oil burners arerelatively ineiiicient and are quite noisy. One cause of this noise isthe pulsating pressure produced in the tube and the combustion chamber.Many of these burners include curved or angularly disposed vanes orother means at the outlet end of the tube to provide a whirling actionin the stream and thereby mix the air with the fuel oil. This turbulenceis another source of noise. Insofar as is known, all types of thesepressure type oil burners are quite noisy, and the ina-in differencebetween various pressure burners, insofar as the apparent noise isconcerned, is in the manner in which the furnace is insulated so` as todeaden the noise.

Another difficulty encountered in operating pressure type oil burnersarises from a tendency to deposit soot on any `relatively cold. surfaceagainst which the partially burned gases impinge or across which thegases flow.. A very slight variation of the burner controls fromtheoptimum settings will result in a large amount of soot.4

Accordingly, it is an object of the present invention to provide animproved apparatus for burning fuel that will effect better mixing ofthe fuel and air and therebt7 burn the fuel with greater efficiency,that will effect complete combustion of the fuel in a relatively shortcombustion zone, that will prevent the deposition of carbon. and thatwill be quiet.

Another obiect of the present invention is to effect better mixing of afuel with a combustion supporting eas. such as air, so as to morequickly and eiciently burn the fuel in a relativelyshort combustionzone.

Another obiect of the present invention is to provide an improvedpressure-type liquid fuel 2. burner which includes a combustion head, anozzle for spraying 'a stream of liquid fuel into the head and means forblowing a relatively smaller Y amount of air into the head along withthe fuel. This improved burner includes air passages arranged todischarge a relatively larger volume of air in the form of relativelyhigh velocity, low pressure jets or streams into and across the path ofthe burning stream of gasified fuel. The low pressure jets inspire thegaseous fuel to effect improved mixing of the air and fuel and moreeilicient combustion. Preferably, the combustion head contains passagemeans arranged to maintain a rotary stream of air about the burningstream of sprayed liquid fuel while the fuel is Figure 3 is an end viewtaken as shown by line.

3-3 on Figure l; and

Figure 4 is a fragmentary sectional View taken along line 4-4 of Figure1.

The present invention will be described in con.- nection with theburning of fuel oil but its principles may be utilized in the burning ofother liquid fuels, and, as will be pointed out, at least some of itsprinciples may be utilized in the burning of gaseous fuels.

Referring to the drawings showing a preferred embodiment of the presentinvention and illustrating a preferred method of burning liquid fuel,the burner shown in. these drawings is intended for burning fuel oil toheat water in a furnace of a hot water heating system. The burner may beused with other types of furnaces and heating systems. The burnerincludes an electric drive motor IIJ mounted on the side of casing II. Afuel oil pump I2 is mounted on the opposite side of casing I I and has ashaft I3 connected to shaft I4 of motor I0 through connector i5. Pump I2is connected through tube` I6 to a tank. not shown, or other suitablesource of fuel. oil is connected through an outlet tube I-I to theburner for supplying oil under pressure upon energization of motor I0.

On the side of casing H, there is mounted a tube I9 and between tube i9and casing Il there is a shield 20, shown only in part. The shield 29may be part of a furnace cover. In the tube I9, there is mounted acombustion head 22 of substantially frusto-conical shape and having aninterior surface 23 dening an elongated combustion chamber 24 having aninlet 25 and outlet 26 at opposite ends. It is to be noted thatcombustion zone 24 has a circular periphery or outline when cut by aplane normal to the length of the zone. An annular wall 21 extendssupstream from the combustion head 22 and the upstream end of wall 21 isclosed by a cap 28. The wall 21 and cap 28 together denne a plenum orchamber 29.

In the bottom of casing Il, there is mounted a tube 3| which extendsthrough cap 28 and has on its outlet end an atomizing nozzle 32centrally arranged in the inlet opening of head 22. The tube 3l isconnected through tube l1 to pump I2 Y so that when the motor I9 isenergized, oil is supplied to nozzle 32 under pressure. Nozzle 32 ispreferably of the type which discharges a substantially conical streamof atomized fuel oil in the form of nely divided droplets, although anozzle which discharges a cylindrical stream may be utilized. A pair ofelectrodes 33 are mounted closely adjacent to nozzle 32 and each isconnected through a conductor 35 to a source of electric current forproducing a spark between the electrodes for igniting the atomized fueloil.

On motor shaft i4, there is mounted a fan 36. When fan 36 is rotated bymotor l0, air is drawn into casing Il through an inlet opening 38 and isforced under pressure into the outer chamber 39. The fan 35 supplies theair for burning the fuel oil. The air flows from chamber 39 throughopening 4i! into a main or fan discharge plenum 42 inside of tube I9.The tube i9 is closed on the downstream side so that no air can flowfrom plenum 42 past the head 22 between head 22 and tube 9. The pressurein plenum 42 is the pressure developed by the fan 36. In Wall 21, thereare a plurality of openings 43 and air flows from the main plenum 42through openings 21 into the primary air plenum 29 and from plenum 29through inlet opening 25 into the combustion zone 24. Thus, a stream ofburning air and fuel oil is blown into and travels longitudinallythrough the combustion zone.

As the burning stream enters the combustion zone 24 through the inlet25, the oil is in the form of small droplets. Enough oil is immediatelyvaporized so that burning is started by the igniter, electrodes 32. Thisinitial burning heats the stream of fuel oil and aids in Vaporizing orgasifying the fuel oil. Conversion of the fuel oil to a gas takes timesso that as the burning stream of fuel oil and air move through theinitial portion of the combustion zone 24, only a small amount of fueloil is burned and most of the liquid fuel oil is being converted to agaseous fuel. As the fuel oil moves through this initial portion and isbeing only partially burned, there is a tendency for the burning streamto deposit carbon on any relatively cold. surface which the streamcontacts In addition, there is some tendency for the initially burningstream to heat the combustion head. While the burning stream will tendto heat the head suinciently to shorten its life, the head wil berelatively. colder and the fact that the head is heated will noteliminate the tendency for coke to be deposited on the internal surfaceof the head. y

In order to prevent the deposition of coke and to prevent overheating ofthe head, a blanketing stream of air is rotated transversely about theburning stream. This blanketing stream of air rotates about theperiphery of the burning stream adjacent the inner surface 23 of head22. The axis of rotation is the longitudinal axis of the combustion zoneas well as the longitudinal axis of the stream extending in thedirection of movement through the combustion zone. A preferred means ofproviding such a blanketing stream of air is shown in the drawings.Extending about the inlet end of head 22 and connected to Wall 21 is awall 45. Wall 45, wall 21 and head 22 together constitute wall meansdefining a scavenging air plenum 46.

Wall 45 contains a plurality of ports 41 communicating with plenums 42and 46 so that air flows from plenum 92 into plenum 49. The combustionhead wall is provided with a plurality of passages 49 arranged in banks48. Referring more particularly to Figure 4, the passages 4t are similarand only one will be described in detail. Each outlet passage 49 has aninlet and outlet and extends tangentially to the inner surface 23 and tothe periphery of combustion zone 24. As shown, each passage 49 extendsin a direction normal to the direction of travel of the burning streamthrough the head. The passages 49 may be inclined forwardly toward theoutlet 26 so as to both direct a stream about the periphery of thecombustion zone and also forwardly toward the outlet 2E. With eitherarrangement, passage 49 is located in a plane tangent to the circularperiphery of the combustion zone and extends in a direction transverseto the direction of travel of the burning stream of fuel oil through thehead. A single wide passage may be substituted for each bank ofpassages. The passages 49 direct a plurality of streams of air about theinner periphery of the head adjacent the inner surface. This rotatingblanket of air primarily prevents the deposition of coke on the surfaceof the head but also reduces heating of the head. This blanket of air issubsequently mixed with the gaseous fuel oil and supports combustion ofthe fuel oil, but in the initial portion of the combustion zone there isa thin layer of substantially pure air next the surface of the head.

The total amount of air discharged into the combustion zone throughinlet 25 and passages 49 is only a small part of the total air requiredto complete combustion of the fuel. The major portion of the airrequired for combustion is added to the burning stream of fuel oil afterthe oil is completely or substantially completely converted to thegaseous state. To complete combustion, a large amount of air must bediffused throughout the gaseous fuel. This mixing or diffusion of gasesnormally takes a relatively long time and extends over a long distanceof flame travel. In accordance with the present invention, the majorportion of air necessary to complete combustion is quickly andthoroughly mixed with the fuel oil and combustion is completed While thefuel oil moves forwardly only a short distance. A large number ofpassages 5l extend through the Wall of head 22 between the banks 48 andoutlet 26. Each passage 5l is in communication with plenum 42 land thepressure drop across the passages is relatively high so that eachpassage directs a high velocity, low pressure jet of air transverselyacross the burning stream of fuel oil. Each jet inspirates gaseous fueloil, and the air and inspirated fuel oil are thoroughly mixed andimmediately burned. When looking atea-,rae

atene: of these bieb velocity iets. is only a very small clear cone. ofair adiaeent the passage; the remainder of the-.iet is, burning.. Thesehigh velocity jets drawin. and, mix with; the fuel oil so` thoroughlythat. combustionf is complete or substantially complete when the streamof burning, gases passes outlet, 2.6. Flames do. not extend` down thetube |19.. and the forwardr or downstream face of the flame will assumethe shape indicated by broken line 52. A very small tip of' flame 53 mayextend. down the center of" tube I9 from the face ofthe main flame. Asshown, each passage l extends toward the middle or central axis of thecombustion zone, but the passages may extend in a directiontransverselyl of or across the combustion zone without extendingdirectlytoward the axis. The passages 5l may extend in a direction normal to theaxis of the combustion zone. Preferably, the passages 5I are parallel toeach other. i

For purposes of illustration and not limitation, there, are l2 passages43 each havinga diameter of fr of' an inch. Thus, the totalcross-sectional area of the passages, 43 is less thanthe area of theinlet 2.5 so that the passages control the flow ofv air. past. thenozzle is.A If desirable. the, inlet may be in directy communicationwith the fan plenum 42 or withV air from adifferent source, but. theinlet 2.5,. would. under such conditions, have to befmore accuratelysized. 'Ijhe structure shown is preferred. Twelve passages 41, eachhaving a diameter of 1%.; of an inch,` are provided in wall 45 forconducting air from plenum 42 into plenum 46. The tangential passages 48each have a diameter of 1%g of an inch so that' their totallcrosssectional area is greater thanthe` total cross-ser tional area ofpassages 41. With this arrangement, the blanketing airv streamdischarged by the passages 49 has a relatively lower velocity than thejets issuing from passages 5| as the pressure drop between the plenum 46and the combustion zone is less than the pressure drop between plenum 42and the combustion zone; The blanketing air stream has a relativelyhighpressure and lower velocity so that this stream does not tend toinspirate gases as do the high velocity lower pressure jets frompassages 5|. The pressure drop across the passages 5l is relatively highso that the air jets issuing from the passages have a relatively highvelocity and low` pressure. Each of the passages has a diametery of 1/8inch, and- '72 passages are arranged in each row. As shown, there are 6rows of 72 passages. Thus, by far the major portion of air forcombustion of the fuel oil is discharged through pas-` sages, 5I, andonly a minor portion of the air is discharged through the inlet passagemeans or the blanketing orscavenging passage means.

The high velocity jets from passages 5l may be used Without thescavenging airblanket from passages 49, especially when the fuel isinitially in a gaseous state when discharged intoy thecombustion zone.The high velocity jets are especially useful when the blanketing streamis used, as

the high velocity jets mix the gasifled fuel oil with this blanketi-ngair when the jets inspirate the surrounding gases of the burning stream.

As shown more clearly in Figure 2, a damper 55.

is mounted in the casing Il and includes' slots 56 which are inclined.Screws 51 extend through the casing Il and the slots 56. `One end 58 ofdamper 55 extends inside of the fan 36. When1 the fan rotates, air isdrawn through. the damper opening at- 5!!` through thelcylindricaldamper 55 and forced into-the chamber 39. When it is dea. sired tochange the amount of air flow, the screws 5l.y may loosenedV and thedamper turned about the.- axis. of. rotationy of. the, fair 36; to moretheA damper longitudinally along` this axis to in` crease or decreaseVthe. portion of the fany 36. which is. blocked by the end 58;. Thus; therate of airv flow and; the pressure, developed in plenum 42v maybereadily adjusted.

Suitable controls` may` be provided for automatically operating theburner and these controls may be, of any welleknown type. When themotor` Il) is` energized', air is supplied to plenum 42 and oil issupplied under pressure to nozzlev 32. Some air flows. into thecombustion zoneY through inlet 2,5 along with the atomized oil, and thisstream of oil and air` is ignited by the igniting means includingelectrodes 33. The burning. stream movesthrough the combustion zone 24to the outlet 26. Asthe burning stream of oil and @air passes throughthe initial portion of' the combustion zone, a blanketing air streamdischarged through the passages. 45 rotates about the peripheryof thecombustion zone and the burning e stream primarily to prevent thedeposition of carbon on the interior surface of the combustion head 22.As the stream moves through a sub.- sequent portion of the combustionzone 24, a large number of high velocity jets are directed inwardly fromthe periphery of the stream and across the stream. These high velocityrelatively lower pressure jets from passages 5I inspire the gaseous fueloil, a part of which has been burned, to form a combustible mixturewhich burns while the burning stream is moving forwardly a relativelyshort distance. The hot gaseous products of combustion move through tubei9 to the. stack and as t-he gases move through the tube they give uptheir heat to the Water surrounding` the tube, and this water may beconfined by an outer casing shown in part at B0. `Combustion is socomplete in the combustion zone that the intera nal surface of the tubeI9 remains bright and clean, andl carbon is not deposited on therelatively cold surface of the tube.

In accordance with the present invention, a burning strearnof fuel oiland a relatively small amount of air is discharged into the inlet end ofa combustion zone and moved through the combustion zone at a relativelylow velocity. As the fuel oil is being converted to the gaseous form, arotating blanket of air is maintained about the periphery of the burningstream to prevent the deposition of' coke on the combustion headdefining the combustion zone. After the fuel oil has been converted to agas, high velocity,'low pressure streams of air are directed inwardlyacross the burning stream to complete combustion. These highvelocityjets contain a major portion of the air necessary to complete combustionof the fuel oil and the jets inspire the gases of the stream. No air isadded subsequently as combustion is complete. The present method ofburning fuel is eillcient. and relativelyv quietand' does not, result.in the deposition of carbon on.

I claim:

1. Apparatus for burning fuel oil comprising an elongated blast tube,means including a combustion head extending across the tube to preventthe ilow of air therebetween past the combustion head which includes awall defining an internal truste-conical combustion zone having an inletopening at the smaller end and an outlet opening at the larger end, wallmeans in the tube dening with the combustion head and the tube a mainplenum on the upstream side of the combustion head, a fan for supplyingair to the main plenum, an atomizing nozzle centrally located in theinlet opening for spraying a stream of fuel into the combustion zone,primary wall means defining a primary air plenum at the upstream side ofthe inlet opening, primary air passages in and extending through theprimary wall means and communicating with primary and main plenumswhereby air flows from the main plenum through the primary plenum andthen through the inlet opening about the nozzle into the `commistionzone, and secondary wall means defining a scavenging air plenum about aportion of the combustion head adjacent the inlet, passages in andextending through the secondary wall means in direct communication withthe main plenum, a plurality of banks of scavenging air ports arrangedabout the periphery of the combustion zone, a passage in the combustionhead and extending from each port through the combustion head wall andterminating in an inlet port indirect communication with the scavengingplenum, the passages of each bank being tangent to the periphery of thecombustion zone.

' 2. Apparatus for burning Vfuel oil comprising an elongated blast tube,means including a com bustion head extending across the tube to preventthe flow of air therebetween past the combustion head which includes awall dening an internal irusto-conical combustion zone having an inletopening at the smaller end and an outlet opening at the larger end, wallmeans in the tube defining with the combustion head and the tube a mainplenum on the upstream side of the combustion head, a fan for supplyingair to the main plenum, an atomizing nozzle centrally located in theinlet opening for spraying a stream of fuel into the combustion zone,primary wall means defining a primary air plenum at the upstream side ofthe inlet opening, primary air passages in and extending through theprimary wall means and communicating with primary and main plenumswhereby air flows from the main plenum through the primary plenum andthen through theinlet opening about the nozzle into the combustion zone,secondary wall means defining a scavenging air plenum about a portion ofthe combustion head adjacent the inlet, passages in and extendingthrough the secondary wall means in direct communication with the mainplenum, a plurality of banks of scavenging air ports arranged about thep-eriphery of the combustion zone, a passage in the combustion headextending from each port through the combustion head wall andterminating in an inlet port in direct communication with the scavengingplenum, the passages of each bank being tangent to the periphery of thecombustion zone, and a plurality of passages in and extending throughthe combustion head wall adjacent the outlet, each having an inlet indirect communication with the main plenum, said last mentioned passagesextending in a direction toward the central longitudinal axis of thecombustion zone for directing jets of air into and across the burningstream of fuel oil.

3. Apparatus for burning fuel oil comprising an elongated blast tube,means including a combustion head extending across the tube to preventthe flow of air therebetween past the combustion head which includes awall defining an internal frusto-conical combustion zone having an inletopening at the smaller end and an outlet opening at the larger end, wallmeans in the tube dening with the combustion head and the tube a mainplenum on the upstream side ofthe combustion head, a fan for supplyingair to the main plenum, an atomizing nozzle centrally located in theinlet opening for spraying a stream of fuelv into the combustion zone,primary wall means defining a primary air plenum at the upstream side ofthe inlet opening, primary air passages in and extending through theprimary wall means and communicating with primary and main plenumswhereby air ilows from the main plenum through the primary plenum andthen through the inlet opening about the nozzle into the combustionzone, secondary wall means defining a scavenging air plenum about aportion of the combustion head adjacent the inlet, passages in andextending through the secondary wall means in direct communication withthe main plenum, a plurality of banks of scavenging air ports arrangedabout the periphery of the combustion zone, a passage in the combustionhead extending from each port through the combustion head wall andterminating in an inlet port in direct communication with the scavengingplenum, the passages of each bank being tangent to the periphery of thecombustion zone, and a plurality or" passages in and extending throughthe combustion head Wall adjacent the outlet, each having an inlet indirect communication with the main plenum, said last mentioned passagesextending in a direction toward the central longitudinal axis of thecombustion zone for directing jets of air into and across the burningstream of fuel oil, the total transverse cross-sectional area of theplurality of passages extending through combustion head wall adjacentthe outlet being greater than the total of the transversecross-sectional area of all of said primary air passages through primarywall means plus the transverse crosssectional area of all of thepassages extending through the secondary wall means.

4. Apparatus for burning fuel oil comprising an elongated blast tube,means including a combustion head extending across the tube to preventthe flow of air therebetween past the combustion head which includes aWall deiining an internal frusto-conical combustion zone having an inletopening at the smaller end and an outlet opening at the larger end, wallmeans in the tube defining with the combustion head and the tube a mainplenum on the upstream side of the combustion head, a fan for supplyingair to the main plenum, an atomizing nozzle centrally located in theinlet opening for spraying a stream of fuel into the combustion zone,primary wall means deiining a primary air plenum at the upstream side ofthe inlet opening, primary air passages in and extending through theprimary wall means and communicating with primary andA main plenumswhereby air flows from the main plenum through the primary plenum andthen through the inlet opening about the nozzle into the combustionzone, the total transverse cross-sectional area of the primary airpassages being less than the open area of the inlet, secondary wallmeans defining a scavenging air plenum about a portion of the combustionhead adjacent the inlet, passages in and extending through the secondarywall means in direct communication with the main plenum, a plurality ofbanks of scavenging air ports arranged about the periphery of thecombustion zone, a passage in the combustion head extending from eachport through the combustion head wall and terminating in an inlet portin direct communication with the scavenging plenum, the passages of eachbank being tangent to the periphery of the combustion zone, the totaltransverse cross-sectional area of the air passages through thesecondary wall means being less than the total area of the passagesextending through combustion head wall, a plurality of passagesextending through the combustion head wall adjacent the outlet, eachhaving an inlet in direct communication with the main plenum, said lastmentioned passages extending in a direction toward the centrallongitudinal axis of the combustion zone for directing jets of air intoand across the burning stream of fuel oil, the total transversecross-sectional area of the plurality of passages extending throughcombustion head Wall adjacent the outlet being greater than the total ofthe transverse cross-sectional area of all of said primary air passagesthrough primary Wall means plus the transverse cross-sectional area ofall of the passages extending through the secondary Wall means.

5. Apparatus for burning fuel oil comprising an elongated blast tube,means including a combustion head extending across the tube to preventthe ilow of air therebetween past the combustion head which includes awall dening an internal frusto-conical combustion zone having an inletopening in the head at the smaller end of the combustion zone and anoutlet opening in the head at the larger end of the combustion zone,wall means in the tube defining with the combustion head and the tube amain plenum on the upstream side of the combustion head, a fan forsupplying air under pressure to the main plenum, an atomizing nozzlecentrally located in the inlet opening for spraying a stream of fuelinto the combustion zone, primary wall means delining a primary airplenum at the upstream side of the inlet opening, primary air passagesin and extending through the primary wall means and communicating withthe primary and main plenums whereby air ows from the main plenumthrough the primary plenum and then through the inlet lil opening aboutthe nozzle into the combustion zone, the total cross-sectional area ofthe primary air passages being smaller than the cross-sectional area ofthe inletopening about the nozzle, secondary Wall means defining asecondary air plenum about a portion of the combustion head adjacent theinlet, passages in andl extending through the secondary wall means indirect communication with the main plenum, a plurality of secondarypassages in the combustion head extending through the combustion headwall and terminating in an inlet port in direct communication with thesecondary plenum and in an outlet port in direct communication with thecombustion zone whereby air flows from the main plenum into thesecondary plenum and then through the secondary passages into thecombustion zone, the total cross-sectional area of the passages throughthe secondary Wall means being less than the total cross-sectional areaof the secondary passages through the combustion head wall and aplurality of jet passages in the combustion head Wall adjacent theoutlet, each of jet passages having an inlet in direct communicationwith the main plenum and an outlet in direct communication with thecombustion zone and extending in a direction to direct the jets of airinto and across the combustion zone, the total cross-sectional area ofthe jet passages being greater than the total cross-sectional area oi.'all the other air passages in the combustion head whereby the majoramount of air discharged into the combustion zone is discharged throughthe jet passages.

FRANK H. CORNELIUS.

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